The chilling threat reported by SITE Intel Group was based on a manifesto published by the jihadists' al Hayat media center – warning the militants "have come to slaughter and smash your ballot boxes."

According to the news site Zero Hedge,the seven-page manifesto titled "The Murtadd Vote"declared: "May Allah make this year’s U.S. presidential election a dreadful calamity like no other to have struck America throughout its pathetic history."

"Murtadd" is a term for an apostate who turns his back on Islam.

The full essay, in English, includes a photograph of Republican presidential nominee Donald Trump, Democratic vice presidential nominee Tim Kaine, as well as a photo Khizr Khan, the father of a Muslim U.S. soldier killed in combat, holding a copy of the Constitution during his speech last July at the Democratic National Convention.

The new threats Saturday came just a day after federal officials have warned authorities in New York City, Texas and Virginia about an unspecific threat of attacks by al-Qaida militants around Election Day.

In response, a Homeland Security official said authorities remained concerned that so-called "homegrown" militants could be inspired to attack within the United States.

"The public should expect to continue to observe an increased law enforcement and security presence across communities in public places," the official told Reuters.

ISIS has called for attacks on American voters on Election Day - and for U.S. Muslims not to cast a vote, a cyber security news and terrorist monitoring group has warned.IS Calls for Attacks on Voters on Election Day, Demands Muslims not Participate in Democratic Process...